this weekend's dyno results

[Gen1GT]

If you get into the 15s, it will depend on your tires. Bring some sticky 15" tires, and get some good 60' times, and you should be into the 15s. Definitely low 16s. Remember that I'm running 15.7 with 117whp and only 2200lbs. 60' times are around 2.27ish. Trap speed should be 88-89ish.

Looking at your dyno graphs, they don't really make much sense. Your mods so far have lost you torque, but got you high RPM power, not such a bad thing really. You'll get some torque back when you put in higher compression pistons with an overbore, and when you can play with your ignition timing with a stand-alone.

But on every dyno graph, torque and horsepower curves are supposed to merge at 5252 RPM(look at mine for reference), because hp is calculated by torque. Dynos don't actually measure hp, they measure torque, then convert it into hp mathematically. ie hp=torque*RPM/5252. Which is why they are equal at 5252. Which is also why there's more hp potential at higher RPM, since the same torque number, just higher in the rev range will get you more power. It's torque more often.

I doesn't make sense to me that dynos be done in 3rd either. The G15M-R used on your engines has 4th gear closer to 1:1 than 3rd.(0.970:1). Check out tranny info here:

http://web2.airmail.net/theman/protegefaq/

And those charts are hard to read without RPM there. It's kind of meaningless to say my car makes such and such hp at 120kph in 3rd.

Anyways, just some thoughts I thought I'd bring up. (dunno)

 

[akhilleus]

I agree with your perspective too and considering what u did to the car twilight your figures should be different...ie higher. But ultimately it doesnt matter because we were able to see the comparisons between various mods. I am also looking forward to your 1/4. I think u will be in the very low 15's w/ that setup. And drag racing isnt that hard...just drive it like u are racing someone from a light on the street, just minimize any traction loss.

 

[Installshield 2]

Correct me if I am wrong guys: The only reason you need to have as close to 1:1 gearing on a dyno is for accurate torque numbers...The formula for HP in terms of power, does not care what the gear ratio is, and as long as the dyno is calibrated accurately the numbers will stay very very close from gear to gear (minus 1st gear, which creates far to quick of a test sample)...

Torque on the other hand, gets multiplied by the gear ratio...and despite most dyno's having the correction data to factor out the "extra" or "less" (depending on what gear ratio you are using) mathmatically, it still isn't ideal for the greatest accuracy...

Is that correct? I haven't heard anything about it in a long while...

 

[Gen1GT]

When you multiply torque in an engine, you multiply horsepower too. There's no such thing as static torque in an internal combustion engine, it's dynamic by nature. If you're producing torque, then you're automatically producing horsepower(or watts). Like I said, dynos measure torque not horsepower. They then use the torque number with RPM to plot a hp line.

HP=Torque*RPM/5252

ie 93lb/ft at 6600RPM=613800

613800/5252=116.9hp

Like I mentioned, it's why torque and hp numbers always merge at 5252RPM on a dyno graph. Unless the torque or hp scales are not the same.

So just say your car makes 100hp at the flywheel. Gearing, not including final drive, says the transmission is turning the axles at 1.310 times the speed of the engine, or 131hp, in 3rd gear. In 4th, it's .970 gearing, or 97hp at the axles, again, not including final drive.

Other than that, I'm not sure how a dyno can know what gear you're in or what your final drive is. I've never heard of anyone punching in that information. I know that 1hp is moving 33,000lbs one foot in one minute, so it could be measured that way without even measuring torque. The faster you move the rolller up to speed, the more power you would get, but limits of gearing would obviously only allow you to go to redline, so lowering gearing would take less time, but not go as far.

Ah man, I think I'm confusing myself here now......(uhm)

 

[Mike R]

It's very easy for the dyno to figure out all of the gearing. You are on a drum that is turned by the tires(the dyno). The engine speed is picked up off the plug wire. That gives a complete final drive ratio including the tires, that's why tire diameter makes such a difference on the dyno. Gearing.

Of course, I am not sure about it. It makes sense though!

 

[fkmp5]

If you get into the 15s, it will depend on your tires. Bring some sticky 15" tires, and get some good 60' times, and you should be into the 15s. Definitely low 16s. Remember that I'm running 15.7 with 117whp and only 2200lbs. 60' times are around 2.27ish. Trap speed should be 88-89ish.

Just more food for thought: last friday I ran a 16.4 and a 16.5 in my P5. you can see the basic bolt-on mods in my signature. temp was mid 70s but the humidity was way up (around 90% and climbing). my 60' times were 2.3 and 2.4 .. i'm still working on the launch. i was on stock 16" wheels/tires .. dropped to 23PSI in the tires..

i'm confident you can get a 15.9 or maybe a little better!!

 

[Installshield 2]

Ok thanks, I don't know much about how dyno's derive the numbers...

But yeah SAE HP is derived from torque through T X RPM/5252, like you mentioned....DIN HP and PS are different calculations from what I remember...

 

[twilightprotege]

gen, i was under the impression that it is best to do a dyno run as close to 1:1, but just as long as the figure isnt below 1:1, so that then rules 4th gear out? anyway, 3rd is what i originally was dyno tested in (gee it hurt my feet ha ha ha), so that's what they are run in. probably at the new dyno place once i have a comparison dyno graph i will get new runs done in 4th if that's the better gear to have them done in...

yeah the dyno i was on was reading speed. the reason the newest figure finishes earlier is because i now have 205/45/16 tyres instead of 195/50/16's. well i guess that's why...

so in reality, and the main question i guess, will 3rd gear or 4th gear yield higher numbers???

another q - how heavy are our cars? 2600lbs ish?

 

[scorch70]

gen, i was under the impression that it is best to do a dyno run as close to 1:1, but just as long as the figure isnt below 1:1, so that then rules 4th gear out? anyway, 3rd is what i originally was dyno tested in (gee it hurt my feet ha ha ha), so that's what they are run in. probably at the new dyno place once i have a comparison dyno graph i will get new runs done in 4th if that's the better gear to have them done in...

yeah the dyno i was on was reading speed. the reason the newest figure finishes earlier is because i now have 205/45/16 tyres instead of 195/50/16's. well i guess that's why...

so in reality, and the main question i guess, will 3rd gear or 4th gear yield higher numbers???

another q - how heavy are our cars? 2600lbs ish?

Hey Twilight, for whether 3rd or 4th gear, here is my dyno showing my results (towards the bottom of the page):

http://www2.msprotege.com/forum/showthread.php?t=62142&page=2&pp=15

Of course, results may vary.

scorch70

 

[twilightprotege]

oh and i should add - i have my new toyo proxes t1-s tyres for stickyness. unfortunately i dont have smaller wheels around

scorch - damn that's a big gain from 3rd to 4th!!! .... but ps - you need engine mounts! the graph is bouncing all over the place!

 

[scorch70]

oh and i should add - i have my new toyo proxes t1-s tyres for stickyness. unfortunately i dont have smaller wheels around

scorch - damn that's a big gain from 3rd to 4th!!! .... but ps - you need engine mounts! the graph is bouncing all over the place!

Yeah, I wondered about the bouncing around. It really didnt feel like it was bouncing all over the damn place on the dyno, but that may be it. I was sort of hoping it was the dyno itself, I hate to add vibration to the P5 just yet. It is still a nice, smooth car to drive (not for long though). Guess I will go pick up at least the front AWR mount. Should help a bit.

/end of threadjack

As for 3rd or 4th gear, I guess it really doesnt matter Twilight. Just stay consistent. Since you've done the others in 3rd, then stay with it. 4th might give you bigger numbers and some bragging rights, but it would be difficult to tell how far you've come from when you starting doing the mods. Since I started with my dynos in 4th, I think Im gonna stick with it. But just like switching dynos, I think consistency is more important. As for bragging rights, I think you are going to be the king of N/A for a while.

scorch70

 

[Gen1GT]

Ya, if you've dynoed in 3rd, you might as well stay in 3rd for consistancy. You're still head of the NA pack...until I dyno my cam that is

I was just told by some guys on the Miata site, that horsepower, although it increases the same time torque does throughout the RPM range, the decrease in axle speed is directly proportional the gearing. ie, more force is being applied, but less often. A 14:1 overall ratio means the torque is multiplied 14 times, but since the axle is moving 14 times as slow, less overall work is being done. It cancels itself out. This would be the math:

HP=gear ratio*(torque*RPM/5252)/gear ratio

Sorry for the earlier misinformation. So it really doesn't matter what gear you your dyno pull in, it's really just for a smooth, long accurate pull. Some cars might bog down at 1500RPM if it was done in 5th though.

Twilight, our cars have the same 3rd and final drive gearing, but my 4th is 1.030:1. It's not like my dyno operator knew that though, and I'm sure he would have done your run in 4th too.

 

[twilightprotege]

maybe at the new dyno place i'll get a run in 3rd and 4th to compair and see what's what...

 

[Lurch]

I added this on a post a while back. Looks like it could bear repeating:

A NOTE ABOUT DYNOS:
Dynos give you a number. Nothing more. If you want to trick yourself into believing that your car has more power than another one that was dynoed on a different machine...even if it is the same brand...you are incorrect. Use dynos as a tuning guide. Take your car to the best dyno you can afford and ALWAYS take it back there for subsequent tuning. Also, ask for 6-7 pulls at the beginning of the day and at the end of the day, not just to baseline, but to check the machine's repeatability. All you are looking at is the delta on your car at YOUR DYNO. In other words, I have seen 200hp on one dyno equal 143 on another. Some of it is how it is "corrected" and some of it is lousy operator or dyno setup.

And they do pulls in 4th gear because that is the closest ratio to 1:1 with the engine speed. 3rd gear pulls are less accurate.

Good luck with your tuning.

 

[scorch70]

I added this on a post a while back. Looks like it could bear repeating:

A NOTE ABOUT DYNOS:
Dynos give you a number. Nothing more. If you want to trick yourself into believing that your car has more power than another one that was dynoed on a different machine...even if it is the same brand...you are incorrect. Use dynos as a tuning guide. Take your car to the best dyno you can afford and ALWAYS take it back there for subsequent tuning. Also, ask for 6-7 pulls at the beginning of the day and at the end of the day, not just to baseline, but to check the machine's repeatability. All you are looking at is the delta on your car at YOUR DYNO. In other words, I have seen 200hp on one dyno equal 143 on another. Some of it is how it is "corrected" and some of it is lousy operator or dyno setup.

And they do pulls in 4th gear because that is the closest ratio to 1:1 with the engine speed. 3rd gear pulls are less accurate.

Good luck with your tuning.

To back up what Lurch said, if anyone has the latest issue of SCC, they have a good article on dyno numbers. It is incredible how different two dynos can be. They dyno'd a Ford Ranger stock, and got anywhere from 174/205 on one dyno, to 132hp/169tq on another. Same truck, no change in mods! Hell, you're almost better making up a number out of the clear blue!


scorch70

 

[Gen1GT]

Ya, I guess dynos are really only tuning. Dynojets have awesome repeatability though....

 

[twilightprotege]

that's why i went back to the dyno i originally went to...

 

[mp5jeff]

Ya, I guess dynos are really only tuning. Dynojets have awesome repeatability though....

reason i don't bother putting my car on one..unless i get a wb and stand alone to tune then it will get used.

 

[Gen1GT]

reason i don't bother putting my car on one..unless i get a wb and stand alone to tune then it will get used.

It's all about tuning. How do I know if a particular mod got me 1hp, 5hp or no hp? Just say I did 4 mods, and it only got me 3hp. How do I know which did what, and what lost me power? For all I know, my intake cam lost me power, I won't know until I dyno it, which is why I dyno every mod. I dynoed my ignition timing, and Airflow Meter flapper door tension, which obviously gave me best results.

 

[mp5jeff]

It's all about tuning. How do I know if a particular mod got me 1hp, 5hp or no hp? Just say I did 4 mods, and it only got me 3hp. How do I know which did what, and what lost me power? For all I know, my intake cam lost me power, I won't know until I dyno it, which is why I dyno every mod. I dynoed my ignition timing, and Airflow Meter flapper door tension, which obviously gave me best results.

yea well to me, unless you do the mod one by one on the same day it won't always be correct(even if you do it won't be 100 percent on), so that's why i choose not to dyno after mods....maybe one day when im finished with the p5 i will put it on a dyno and see what she reads but untill then its a waste of my time/money.(for ME at least..)